1. Field of the Invention
The present invention relates to a deflection yoke. More particularly, it relates to a deflection yoke to be attached to a television picture tube.
2. Description of the Related Art
A conventional deflection yoke is shown in FIGS. 5-7. In FIGS. 1-7 reference numeral 1 designates a saddle-toroidal type deflection yoke comprising a horizontal deflection coil 2 having a winding wound in a saddle shape, a high magnetic permeable core 4 disposed at the outside of the horizontal deflection coil 2 through a separator 3 made of a synthetic resinous material and a vertical deflection coil 5 wound in a toroidal shape.
In the conventional deflection yoke having the above-mentioned structure, when a deflecting current having a saw tooth wave is supplied for the scanning of the horizontal and vertical deflection coils 2, 5, a deflection magnetic field is produced. There are simultaneously produced an alternating current transmission loss (a copper loss, an eddy current loss and a surface loss) in the coils 2, 5 and an iron loss (a hysteresis loss and an eddy current loss) in the core 4. These losses become large as the frequency of the deflection current flowing in the coils 2, 5 is high and the intensity of the deflection current is high. Recently, a method of increasing the frequency of a deflecting current to the horizontal deflection coil 2 has been employed to increase the resolution power of a picture image. Further, a wide-angle deflection characteristic has been required to obtain a large display area. This requires a large amount of a deflecting current. Accordingly, the temperature of each element in the deflection yoke 1 is further increased, whereby problems such as a change of convergence due to deterioration in the characteristics of the core 4, the deformation of the separator 3 and the deformation of the deflection yoke, and/or reduction in the durability of the deflection yoke 1 due to the thermal deterioration of the insulating material are caused.
In the conventional deflection yoke, although attempts have been made to increase the cross-sectional area of the deflection coil and the volume of the core or to provide a cooling fan in order to suppress a temperature rise at each of the elements of the deflection yoke 1 which is caused by supplying a large amount of a deflecting current having a high frequency to the horizontal deflection coil 2 for the purpose of obtaining a high resolution power and a wide-angle deflection characteristic, there still remains a problem that a sufficient cooling effect can not be obtained in a case, in particular, of a type that the scanning is conducted at a high frequency of 130 kHz or having a wide-angle deflection of 110.degree..